Laser irradiation stage, laser irradiation optical system, laser irradiation apparatus, laser irradiation method, and method of manufacturing a semiconductor device

ABSTRACT

As the output of laser oscillators become higher, it becomes necessary to develop a longer linear shape beam for a process of laser annealing of a semiconductor film. However, if the length of the linear shape beam is from 300 to 1000 mm, or greater, then the optical path length of an optical system for forming the linear shape beam becomes very long, thereby increasing its footprint size. The present invention shortens the optical path length. In order to make the optical path length of the optical system as short as possible, and to increase only the length of the linear shape beam, curvature may be given to the semiconductor film in the longitudinal direction of the linear shape beam. For example, if the size of the linear shape beam is taken as 1 m×0.4 mm, then it is necessary for the optical path length of the optical system to be on the order of 10 m. If, however, the semiconductor film is given curvature with a radius of curvature of 40,000 mm, then the optical path length of the optical system can be halved to approximately 5 m, and a linear shape beam having an extremely uniform energy distribution can be obtained.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a stage for specifying a shapeof an irradiation surface onto which a laser beam is irradiated.Further, the present invention relates to a laser irradiation apparatusin which energy distribution of a laser beam is made uniform over acertain specific region. The present invention also relates to a methodof making an energy distribution uniform, and to an optical system torealize the uniformity. Furthermore, the present invention relates to amethod of making the energy distribution of a laser beam uniform over acertain specified region, and to a method of annealing a semiconductorfilm using the laser beam (the method is hereafter referred to as “laserannealing”). The present invention also relates to a method ofmanufacturing a semiconductor device, the semiconductor device havingcircuits structured by thin film transistors (hereafter referred to as“TFTs”), which includes a laser annealing process. For example,electro-optical devices. typically liquid crystal display devices, andan electronic equipment in which such an electro-optical device ismounted as a part, are all included in the category of the semiconductordevices. Namely, the term “semiconductor device” as used throughout thespecification indicates general devices capable of functioning byutilizing semiconductor device characteristics, and electro-opticaldevices, semiconductor circuits. and electronics all fall under thecategory of semiconductor devices.

[0003] 2. Description of the Related Art

[0004] Techniques for performing crystallization, or for increasingcrystallinity, by performing laser annealing of amorphous semiconductorfilms or crystalline semiconductor films (semiconductor films that arenot single crystal, but have crystallinity such as poly-crystallinity ormicro-crystallinity), in other words non-single crystal semiconductorfilms formed on an insulating substrate such as glass have beenundergoing widespread research recently. Films such as silicon films areoften used as the semiconductor films.

[0005] Glass substrate are low cost, and can be easily made into largesurface area substrates, compared with conventional quartz substrates,which are often used. This is because the above research is activelyperformed. Lasers can impart a high energy to only a non-single crystalsemiconductor film, without causing much change in the temperature of asubstrate, and therefore lasers are suitable for annealing semiconductorfilms formed on the glass substrates having low melting pointtemperature (the distortion temperature of generally available glasssubstrate is on the order of 600° C.).

[0006] Crystalline semiconductor films formed by laser annealing havehigh mobility. The manufacture of TFTs on a single glass substrate, usedfor driving pixels and used in driver circuits, by using the crystallinesemiconductor films is therefore flourishing, along with the manufactureof active matrix liquid crystal electro-optical devices. The crystallinesemiconductor films are made from many crystal grains, and thereforethey are also referred to as polycrystalline semiconductor films.

[0007] In laser annealing, a method in which a laser beam of a pulseoscillation type excimer laser or the like having high output is formedby an optical system so as to have a square shape spot of severalcm/square, or a linear shape with a length equal to or greater than 10cm, on an irradiation surface, and then scanning of the laser beam isperformed (the irradiation position of the laser beam is made to moverelative to the irradiation surface) is preferably used because it hasgood productivity and is industrially superior.

[0008] In particular, if a linear shape laser beam (hereafter referredto as a linear shape beam) is used, then the laser beam can beirradiated over the entire irradiation surface by scanning only in adirection perpendicular to the longitudinal direction of the linearshape beam. This differs from a case of using a spot shape laser bean,with which it is necessary to scan forward and backward, left and right,and therefore high productivity can be obtained. Scanning in a directionperpendicular to the longitudinal direction is performed because thatscanning direction has the best efficiency. Due to their highefficiency, linear shape beams formed by appropriate optical systems arebeing used mainly in laser annealing processes. Note that, within thisspecification, the direction of the long side of the linear shape beamis referred to as a longitudinal direction, while the short side isreferred to as a transverse direction.

[0009] An example of an optical system for forming the shape of a laserbeam into a linear shape on an irradiation surface is illustrated. Theoptical system shown in FIG. 2 is an extremely general one. The opticalsystem not only converts the shape of the laser beam into a linear shapeon the irradiation surface, but at the same time it makes the energydistribution of the laser beam uniform. In general, optical systems formaking the beam energy distribution more uniform are referred to as beamhomogenizers. The optical system shown in FIG. 2 is one of beamhomogenizers.

[0010] Synthetic quartz may be used in all cases, for example. as thebase material of the optical light system, provided that an excimerlaser to be an ultraviolet light is used as a light source. This is truebecause a high transmissivity can be obtained. Further, there may beemployed a coating material capable of obtaining a transmissivity of 99%or more with respect to the wavelength of the excimer laser used as acoating.

[0011] The side view of FIG. 2 is explained first. A plane containingthe light axis and parallel to the page of the side view is taken as ameridional plane, and a plane containing the light axis andperpendicular to the meridional plane is taken as a sagittal plane. Thedirection of the light axis changes here for cases in which it isnecessary to bend the light path by using mirrors or the like due to thelayout of the optical system, and it is assumed that the meridionalplane and the sagittal plane also change at this time. A laser beamoutput from a laser oscillator 1201 is divided in a directionperpendicular to the sagittal plane by cylindrical lens arrays 1202 aand 1202 b. With this structure, there are four cylindrical lensescontained in the cylindrical lens array 1201, and therefore fourdivisions are made. It is assumed that the number of cylindrical lensescontained in the cylindrical lens array 1202 b is also four. The dividedlaser beams are made to mutually overlap in a certain plane by acylindrical lens 1204. It is not always necessary to use the twocylindrical lens arrays 1202 a and 1202 b; one cylindrical lens arraymay also be used. The advantages of using two cylindrical lens arraysare that the size of the linear shape beam can be changed, and that thewidth of the linear shape beam in the transverse direction can be madeshorter.

[0012] The once again divided laser beams are bent at a right angle by amirror 1207, and then made to once again overlap on an irradiationsurface 1209 by using a doublet cylindrical lens 1208. The doubletcylindrical lens designates a lens structured by two cylindrical lenses.Uniformity of the energy distribution is thus formed in the transversedirection of the linear shape beam, and the width in the transversedirection of the linear shape beam is determined. The mirror 1207 isused in order to make the irradiation surface into a level surface, andis not always necessary.

[0013] The upper view of FIG. 2 is explained next. The laser beamemitted from the laser oscillator 1201 is divided in a directionperpendicular to the meridional plane by the cylindrical lens array1203. There are seven lenses contained in the cylindrical lens array1203 with this structure, and therefore the laser beam is divided intoseven divisions. Two cylindrical lens arrays 1203 may also be used inorder to change the length of the linear shape beam in the longitudinaldirection. The laser beams are then made to overlap into one beam on theirradiation surface 1209 by a cylindrical lens 1205. Shown from themirror 1207 forward by dashed lines are the correct light paths, and thepositions of the lens and the irradiation surface, for a case in whichthe mirror 1207 is not disposed. Uniformity of the energy distributionin the longitudinal direction of the linear shape beam is thus formed,and the length of the linear shape beam in the longitudinal direction isdetermined.

[0014] The length L of the linear shape beam is determined by thefollowing elements: a width d of the cylindrical lenses contained in thecylindrical lens array 1203; a focal length f1 of the cylindricallenses; and a focal length f2 of the cylindrical lens 1205. This isexplained while following FIG. 3. A cylindrical lens 1301 is structuredby cylindrical lenses having a width d. A laser beam made incident tothe cylindrical lens array 1301 is condensed into a plurality ofpositions by the location of the focal length f1. The laser beam thenbecomes incident to a cylindrical lens 1302 while expanding. Thecylindrical lens 1302 is a convex lens, and therefore two parallel lightfluxes within the figure are each concentrated at positions located at adistance f2 behind the cylindrical lens 1302. The distance f2 is thefocal length of the cylindrical lens 1302. The laser beams that are eachincident to the cylindrical lens array 1301 are thus converted to alinear shape beam having a length L. A simple calculation shows that:

[0015] [Eq. 1]

[0016] As explained above, the cylindrical lens array 1202 a, thecylindrical lens array 1202 b, and the cylindrical lens array 1203function as lenses that divide the laser beam. The obtained uniformityof the laser beams is determined by the number of divisions. With theaforementioned structure, there are four divisions by seven divisions,and therefore a total of 28 divisions are formed.

[0017] By irradiating the linear shape beam thus formed in accordancewith the above structure so as to be overlapped while gradually shiftingthe beam in the transverse direction, laser annealing can be performedwith respect to the entire surface of a non-single crystal silicon film,for example, and the crystallization can be achieved and thecrystallinity of the film can be increased.

[0018] The shape of laser beams emitted from excimer lasers is generallyrectangular, falling with an aspect ratio range of approximately one tofive. The laser beam strength shows a Gaussian distribution in which itbecomes stronger toward the center. The size of the laser beam can beconverted, for example, into a uniform energy distribution 300 mm×0.4 mmlinear shape beam by the optical system shown in FIG. 2.

[0019] According to an experiment performed by the applicants of thepresent invention, the overlap pitch is most suitably set toapproximately {fraction (1/10)}th of the width of the linear shape beamin the transverse direction when irradiating a linear shape beam ofpulse oscillation with respect to a semiconductor film. Namely, if thewidth in the transverse direction of the linear shape beam is 0.4 mm,then laser annealing may be performed while shifting the semiconductorfilm in the transverse direction of the linear shape beam by 0.04 mmduring the time from one pulse of light is emitted until the next pulseof light is emitted. The uniformity of laser annealing of thesemiconductor film is thus increased. The method discussed thus far isan extremely general method used in order to perform laser annealing ofa semiconductor film by using a linear shape beam.

[0020] The increasingly high output of laser oscillators has beenremarkable recently, and laser oscillators capable of having a linearshape beam length exceeding 300 mm have become available. However, thesubstrate size used in production plants has also changed, and 600mm×720 mm substrates, and 1000×1200 mm substrate are now planned, forexample. A length on the order of 300 mm for the linear shape beam isbecoming insufficient. If a case of annealing a semiconductor filmformed on a 600 mm×720 mm substrate, for example, using a 300 mm longlinear shape beam is considered, the longitudinal direction of thelinear shape beam and the short side (the side having a length of 600mm) of the substrate may be disposed in parallel. Half of the substratesurface can be laser annealed by scanning relatively the substrate withrespect to the linear shape beam over a distance of 720 mm with in thedirection of the long side of the substrate. Provided that the remaininghalf surface then undergoes laser annealing by the similar method, theentire surface of the substrate can be laser annealed.

[0021] There is exerted a bad influence on the throughput and on thefootprint if laser annealing is performed by this type of method, namelyscanning of the substrate (or the linear shape beam) must be performedtwo or more times, and the substrate (or the linear shape beam) must bemoved forward and backward, and left and right. Furthermore, if laserannealing is performed on one half of the substrate at the time usingthe linear shape beam, then one half of the semiconductor film is laserannealed uniformly. However, uniformity is lost in the vicinity of theboundary between the one and the other half of the semiconductor film,and it is difficult to form semiconductor elements in this portion.Looking at these problem points, it becomes clear that it is preferableto make the length of the linear shape beam in the longitudinaldirection at least on the same order as the length of the short side ofthe substrate.

[0022] However, there is a tendency for the path length of the opticalsystem to become longer in order to form a long linear shape beam. Forexample, an optical path length on the order of 5000 mm is necessary tomake a 300 mm long linear shape beam, further the optical path lengthwill exceed 10,000 mm in order to make a 1000 mm long linear shape beam.

SUMMARY OF THE INVENTION

[0023] An object of the present invention is to determine what type ofoptical system is necessary in forming a very long linear shape beam,and what type of laser irradiation apparatus may be manufactured, toprepare the future when a high output laser oscillator is put into apractical use. Further, an object of the present invention is to providea laser irradiation apparatus having a very small footprint.

[0024] A laser beam having a uniform energy distribution on a substrateis formed by forming a substrate into a shape having curvature (at leastone curvature). In other words, the essence of the present invention isthat the focus position of a linear shape beam is adjusted by providingcylindrical shape curvature to a substrate, and a substrate, inparticular a large surface area substrate, is laser annealed by a linearshape beam allowing an extremely uniform energy distribution. Largesurface area substrates bend very easily, and therefore it is possibleto easily form the curvature necessary for the present invention. Manytypes of processes can be performed by using the laser beam, such ascrystallization of semiconductor films, and activation of impurityelements.

[0025] Further, with employment of the present invention, it is alsopossible to make the optical path length of an optical system forforming a conventional linear shape beam, or for forming a linear shapebeam shorter than a conventional beam, shorter than the optical pathlength of a conventional optical system. In this case, the substratebecomes relatively small, and therefore curvature can be easily given tothe substrate if a flexible substrate or the like is used instead of ahard substrate such as a glass substrate. It is therefore preferable touse a flexible substrate.

[0026] The structure of the present invention relating to a laserirradiation stage is that an irradiation surface for a beam expanded ina single direction has a shape having curvature in a direction parallelto the single direction.

[0027] Further, the structure of the present invention relating to alaser irradiation optical system has a first means for expanding a beamin a single direction, and a second means for establishing anirradiation surface for the beam expanded in the single direction. Thesecond means gives the irradiation surface a shape having curvature in adirection parallel to the single direction.

[0028] In the aforementioned structure, the first means or the secondmeans contains a cylindrical lens array or a cylindrical lens. Thecylindrical lens array can expand a laser beam in a single direction,make the beam uniform, or perform both actions. Further, the cylindricallens can concentrate a laser beam in a single direction. A laser beamcan be expanded, made uniform, and condensed in a single direction bycombining the two types of lenses, and a laser beam can be expanded,made uniform, and condensed in each of two orthogonal directions bydisposing the two types of lenses at right angles to each other.

[0029] Further, the structure of the present invention relating to alaser irradiation apparatus has a laser oscillator, a first means forexpanding a laser beam emitted from the laser oscillator in a firstdirection, a second means for condensing the laser beam in a seconddirection orthogonal to the first direction, and a third means forestablishing an irradiation surface and for moving the irradiationsurface relative to the laser beam in the second direction. The thirdmeans gives the irradiation surface a shape having curvature in adirection parallel to the first direction.

[0030] In the above structure, it is preferable that the laseroscillator combined with the present invention have high output in awavelength region that is well absorbed by semiconductor films. If asilicon film is used as a semiconductor film, then it is preferablethat, considering the absorption index, the wavelength of the laser beamemitted from the laser oscillator used be equal to or less than 600 nm.Excimer lasers, YAG lasers (higher harmonic waves) and glass lasers(higher harmonic waves) may be used, for example, as laser oscillatorsfor emitting this type of laser beam.

[0031] Further, lasers such as YVO₄ lasers (higher harmonic waves), YLFlasers (higher harmonic waves), YAlO₃ lasers, glass lasers, ruby lasers,alexandrite lasers, Ti:sapphire lasers, Ar lasers, Kr lasers, CO₂lasers, helium cadmium lasers, copper vapor lasers and metallic vaporlasers may be used, for example, as laser oscillators with wavelengthssuitable for crystallization of a silicon film. In addition, continuousoscillation type laser oscillators can be applied to the presentinvention.

[0032] In the above structure, the first means or the second meanscontains a cylindrical lens array or a cylindrical lens.

[0033] The structure of the present invention relates to a method oflaser irradiation including expanding a laser beam emitted form a laseroscillator in a first direction; condensing the laser beam in a seconddirection orthogonal to the first direction; and irradiating the laserbeam to an irradiation surface while moving the laser beam relative tothe irradiation surface in the second direction. The irradiation surfacehas a shape having curvature in a direction parallel to the firstdirection.

[0034] In the aforementioned structure, it is preferable that thewavelength of the laser beam emitted form the laser oscillator be equalto or less than 600 nm. Excimer lasers, YAG lasers (higher harmonicwaves), and glass lasers (higher harmonic waves) can be used, forexample. as laser oscillators that emit the above-mentioned laser beam.Further, lasers such as YVO₄ lasers (higher harmonic waves), YLF lasers(higher harmonic waves), YAlO₃ lasers, glass lasers, ruby lasers,alexandrite lasers, Ti:sapphire lasers, Ar lasers, Kr lasers, CO₂lasers, helium cadmium lasers, copper vapor lasers, and metallic vaporlasers may be used. for example. In addition, continuous oscillationtype laser oscillators can be applied to the present invention, besidesthe pulse oscillation type lasers.

[0035] Further, the structure of the present invention relates to amethod of manufacturing a semiconductor device including: expanding alaser beam emitted from a laser oscillator in a first direction;condensing the laser beam in a second direction orthogonal to the firstdirection; and irradiating the laser beam to a semiconductor film whilemoving the laser beam relative to the semiconductor film in the seconddirection, thereby performing annealing of the semiconductor film. Thesemiconductor film is established in a shape having curvature in adirection parallel to the first direction.

[0036] It is preferable that the wavelength of the laser beam emittedform the laser oscillator be equal to or less than 600 nm in theabove-stated structure. Excimer lasers, YAG lasers (higher harmonicwaves), and glass lasers (higher harmonic waves) can be used. forexample, as laser oscillators that emit the above-mentioned laser beam.Further, lasers such as YVO₄ lasers (higher harmonic waves), YLF lasers(higher harmonic waves), YAlO₃ lasers, glass lasers, ruby lasers,alexandrite lasers, Ti:sapphire lasers, Ar lasers, Kr lasers, CO₂lasers, helium cadmium lasers, copper vapor lasers, and metallic vaporlasers may be used, for example. In addition, continuous oscillationtype laser oscillators can be applied to the present invention, besidesthe pulse oscillation type lasers.

[0037] It becomes possible to form a very long laser beam (inparticular, a linear shape beam) having uniformity on an irradiationsurface by applying the present invention. In addition, an opticalsystem for forming this type of laser beam is a laser irradiationapparatus having a small footprint, and therefore is not made large insize. The optical system is particularly effective when set in a cleanroom having high cost per unit surface area. The characteristics ofsemiconductor films manufactured using this type of laser beam becomeuniform, and the electrical characteristics of TFTs, and by extension,the operating characteristics of semiconductor devices, are bothimproved. A reduction in cost of the semiconductor device can also beachieved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In the accompanying drawings:

[0039]FIG. 1 is a diagram for explaining an embodiment mode;

[0040]FIG. 2 is a diagram for explaining a conventional optical system;

[0041]FIG. 3 is a diagram for explaining an optical system;

[0042]FIGS. 4A and 4B are diagrams showing the energy distribution of alinear shape beam;

[0043]FIGS. 5A and 5B are diagrams showing the focus position of alinear shape beam;

[0044]FIG. 6 is a diagram showing the energy distribution of a linearshape beam;

[0045]FIGS. 7A and 7B are diagrams showing the energy distribution of alinear shape beam;

[0046]FIGS. 8A and 8B are diagrams showing the energy distribution of alinear shape beam;

[0047]FIG. 9 is a graph showing the relation between the focal length ofa condenser lens, which makes the energy distribution in thelongitudinal direction of a linear shape beam more uniform, and theradius of curvature imparted to an irradiation surface;

[0048]FIGS. 10A to 10D are cross sectional diagrams showing a process ofmanufacturing a pixel TFT and a driver circuit TFT;

[0049]FIGS. 11A to 11C are cross sectional diagrams showing the processof manufacturing a pixel TFT and a driver circuit TFT;

[0050]FIG. 12 is a cross sectional diagram showing the process ofmanufacturing a pixel TFT and a driver circuit TFT;

[0051]FIG. 13 is an upper view showing the structure of a pixel TFT;

[0052]FIG. 14 is a cross sectional diagram showing a process ofmanufacturing an active matrix liquid crystal display device;

[0053]FIG. 15 is a cross sectional diagram of a driver circuit and apixel portion of a light emitting device;

[0054]FIGS. 16A and 16B are an upper view of a light emitting device,and a cross sectional diagram of a driver circuit and a pixel portion ofthe light emitting device, respectively;

[0055]FIGS. 17A to 17F are diagrams illustrating examples ofsemiconductor devices;

[0056]FIGS. 18A to 18D are diagrams illustrating examples ofsemiconductor devices; and

[0057]FIGS. 19A to 19C are diagrams illustrating examples ofsemiconductor devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] Embodiment Mode

[0059] An embodiment mode of the present invention will be explainedwith reference to FIGS. 5A and 5B.

[0060]FIGS. 5A and B show a simple view of the positional relationshipbetween the curvature direction of a substrate and an optical system. InFIG. 5A, reference numeral 1501 denotes an optical system for expandinga laser beam in one direction, and a laser beam (illustrated within thefigures by dashed lines having arrowheads A, B, and C) that has beenexpanded by the optical system 1501 is formed into a thin linear shapeby a cylindrical lens 1502. A substrate 1503 has curvature in thelongitudinal direction of the linear shape beam such that the nearer tothe edge of the substrate 1503, the shorter the distance from thesubstrate 1503 to the cylindrical lens 1502 becomes. In other words, thecurvature is preferably provided in a negative direction with respect tothe direction that the laser beam advances; namely, the center of theradius of curvature is formed at a position from the substrate on theside of a laser oscillator. A linear shape beam 1504 thus is formedalong the curvature of the substrate. The applicants of the presentinvention performed a simulation that determined that a radius ofcurvature on the order of 10,000 to 100,000 mm is suitable. Thecurvature is changed into a numerical value by the term “radius ofcurvature” in this specification in order to make its expression easier,but the curvature is gentle, and therefore it is not always necessarythat the substrate be on a completely round circle. The radius ofcurvature depends greatly on the structure of the optical system, andtherefore it is necessary to decide on the radius of curvature inconcert with the design of the optical system. The height differencebetween the substrate edge and the substrate center is extremely gentleat several mm when forming curvature having a radius of curvature ofseveral ten thousands of mm, and therefore it is possible to form thiscurvature without placing any load on the substrate. The substrate hasnormally a thickness on the order of 1 mm or less, and it becomes moreeasy to form curvature the larger the surface area of the substrate.Methods such as a method of placing the substrate on a stage alreadyhaving curvature, and a method of supporting the substrate by pins, andincreasing the pin height toward the edges of the substrate can beconsidered for providing curvature. Further, if height of each of pinsis freely changed, operators freely set a size of curvature at arbitrarypoint of the substrate. It is possible to very easily form curvature, nomatter which method is employed.

[0061] The focus position of the cylindrical lens 1502 is explainedaccording to FIG. 5B. FIG. 5B is a diagram viewed from the direction ofthe arrows of FIG. 5A. The aggregation of focus positions (laser beamfocal point positions due to the cylindrical lens 1502) of the incidentlaser beam expanded by the cylindrical lens 1502 have curvature along acurved line 1505. That is, laser beams incident to the cylindrical lens1502 with focal positions on a diagonal, such as the laser beam A and C,will have a focus position that shifts upward (to the side of thecylindrical lens 1502), as compared with laser beams incident to thecylindrical lens 1502 from straight on, like the laser beam B. Thepresent invention corrects the shifts. The shifts in focus positionoccur when changing the shape of a rectangular shape beam having anextremely uniform energy distribution into a linear beam, and thereforethe present invention can also be applied in an optical system forforming only a linear shape beam from a beam having a uniform energydistribution.

[0062] It thus becomes possible with the present invention to correctthe shift in the laser beam focus on an irradiation surface by givingcurvature to the substrate. In addition, the optical path length of anoptical system for forming a laser beam having a predetermined shape(for example, a linear shape beam) in the irradiation surface can bemade shorter with the present invention. The footprint of a laserirradiation apparatus having this type of optical system becomessmaller. and therefore the present invention is particularly effectivewhen set in a clean room having an extremely high unit price per surfacearea.

[0063] Embodiments

[0064] Embodiment 1

[0065] An embodiment of the present invention is explained using FIG. 1.

[0066] First, a 1000 mm×1200 mm×0.7 mm glass substrate is prepared. Aninsulating film is formed on one surface of the glass substrate by aknown method (such as sputtering, plasma CVD, or reduced pressure CVD).Substrates made from glass such as barium borosilicate glass or aluminumborosilicate glass can be given as examples of the glass substrate. Theinsulating film may be formed using a silicon oxide film or the like,with a film thickness on the order of 200 nm. The insulating filmfunctions as a blocking layer such that substances such as alkalinemetal harmful to a semiconductor device do not incur upon the amorphoussilicon film from the glass substrate. Note that quartz substrates,silicon substrates, plastic substrates, metallic substrates, stainlesssteel substrates, flexible substrates, and the like can also be used inaddition to glass substrates. Further, flexible substrates having a filmshape and made from materials such as PET, PES, PEN, or acrylic. Using aflexible substrate, lighter weight can be anticipated provided that asemiconductor device is manufactured. The durability of a flexiblesubstrate can be increased provided that a single layer, or multiplelayer, of barrier layer made from an aluminum film (such as AlON, AlN,or AlO), a carbon film (such as DLC (diamond like carbon)), SiN, or thelike is formed on the front surface, or the front and rear surfaces, ofthe flexible substrate. It is therefore preferable to form such abarrier layer.

[0067] A non-single crystal semiconductor film is then formed on theinsulating film by using a known method. An amorphous silicon film isformed having a thickness of 55 nm as the non-single crystalsemiconductor in embodiment 1. Note that it can be easily projected thatthe present invention can also be applied to other non-single crystalsemiconductors. For example, a compound semiconductor film having anamorphous structure, such as an amorphous silicon germanium film, mayalso be used as the non-single crystal semiconductor. Alternatively, apolycrystalline silicon film may also be used as the non-single crystalsemiconductor, as shown in an example of a manufacturing method in alater embodiment.

[0068] The substrate on which the non-single crystal semiconductor isformed is then subjected to heat treatment for one hour at 450° C. in anitrogen atmosphere. This process is performed for reducing theconcentration of hydrogen within the amorphous silicon film. If theamount of hydrogen within the film is too large, then the film cannotendure the energy of a laser, and therefore this process is performed. Aconcentration on the order of 10²⁰/cm³ is suitable for the hydrogenconcentration within the film. The value “10²⁰/cm³” as used here denotesthat 10²⁰ hydrogen atoms exist per 1 cm³ of the film. It is alsopossible to perform this process in a very short period of time by anRTA (rapid thermal annealing) process. The optimal conditions for theRTA process differ greatly in accordance with the light source andprocessing method used, and therefore the conditions must be suitablydetermined by the operator.

[0069] The process is performed using a pulse oscillation XeCl excimerlaser having an oscillation wavelength of 308 nm as a laser oscillatorin embodiment 1, for example. If the maximum output of the excimer laseris on the order of 3 J per pulse, then it is possible to sufficientlycrystallize the amorphous silicon film by forming a 1000 mm×0.4 mmlinear shape beam.

[0070] An example of a laser irradiation apparatus used in embodiment 1is illustrated in FIG. 1. A laser beam emitted from a laser oscillator1101 is converted into a predetermined shape by a beam expander 1102before being incident to an optical system. The beam expander usesnormally a Galileo type telescope, and the energy concentration of thelaser beam is thus reduced, making the load on the optical systemsmaller, alternatively, may also function as a role that optimizes theshape of the laser beam made incident to the optical system. That is, ifa laser beam having a spot that is very small is made incident to theoptical system, then the number of divisions of the laser beam becomesfewer, and the level of energy distribution uniformity drops. On theother hand, if a laser beam having a very large spot size is madeincident to the optical system, then the effective diameter of theoptical system will be exceeded, and an energy loss will occur. The beamexpander magnification may be determined by considering the aboveissues. The beam expander may be formed by using a cylindrical lens, andmay also be formed by using spherical lenses. When it is desired toexpand a laser beam by same magnification in the vertical and horizontaldirections, it may be formed by spherical lenses, however, when theabove is conducted by different magnification, it is formed bycylindrical lenses. If it is desired to expand a laser beam by differentmagnification factors in the vertical and horizontal directions, thentwo beam expanders structured by cylindrical lenses may be used. Thesize of the laser beam emitted from the laser oscillator is set to 13×35mm in embodiment 1. This size is for a typical high output excimerlaser. In order to decrease the energy concentration of the laser beamas much as possible, the beam is expanded by a magnification of 1.8times, for example, by using a beam expander structured by a sphericallens. Namely, the laser beam size becomes 23 mm×63 mm. In this opticalsystem. a plane parallel to the width (23 mm) of the transversedirection of the laser beam containing the light axis of the laser beamis defined as a meridional plane, and a plane parallel to the length (63mm) of the longitudinal direction containing the light axis of the laserbeam is defined as a sagittal plane. Note that, for cases in which amirror is placed within the optical path, it is assumed that themeridional plane and the sagittal plane each change in accordance withchanges in the optical path due to the mirror.

[0071] The laser beam, converted into a desired magnification by thebeam expander 1102, is then made incident upon a cylindrical lens array1103. Cylindrical lenses structuring the cylindrical lens array 1103 areplanoconvex lenses having a length of 60 mm, a width of 2 mm, athickness of 5 mm, and a radius of curvature equal to 4 mm. If the laserbeam is made incident from a convex plane, then the refraction power isscattered preferably. Note that the radius of curvature is taken asalways provided in the transverse direction within this specification.Thirty five of the cylindrical lenses are lined up in an array, formingthe cylindrical lens array 1103 with dimensions of 60 mm×70 mm×5 mm.Note that, for simplicity, 7 cylindrical lenses are illustrated inFIG. 1. The transverse direction of the cylindrical lens array 1103 isplaced parallel to the sagittal plane. The laser beam is thus dividedinto a plurality of beams, and each of the beams is greatly expanded.

[0072] The laser beam exits the cylindrical lens array 1103, passesthrough a space of 120 mm, and is made incident to a cylindrical lens1104. The cylindrical lens 1104 is a planoconvex lens having a length of60 mm, a width of 150 mm, a thickness of 20 mm. and a radius ofcurvature equal to 2140 mm. The laser beam is made incident from theconvex surface. The transverse direction and the sagittal plane aredisposed in parallel. The laser beams divided by the cylindrical lensarray 1103 are thus made to mutually overlap in a certain plane. Thecombination of the cylindrical lens array 1103 and the cylindrical lens1104 is similar to the optical system explained by FIG. 3.

[0073] The laser beam emitted from the cylindrical lens 1104 is madeincident to a cylindrical lens array 1105 a after passing through a 395mm space. The cylindrical lens array 1105 a has 16 planoconvexcylindrical lenses lined up in an array, with each lens having a lengthof 150 mm, a width of 2 mm, a thickness of 5 mm, and a radius ofcurvature of 100 mm. In other words, the cylindrical lens array 1105becomes a lens having dimensions of 150 mm×32 mm×5 mm. The transversedirection and the meridional plane are disposed in parallel. The laserbeam exits from the cylindrical lens array 1105 a, passes through anopening of 65 mm, and is made incident to a cylindrical lens array 1105b. The cylindrical lens array 1105 b has 16 planoconcave lenses lined upin an array, with each lens having a length of 150 mm, a width of 2 mm,a thickness of 5 mm, and a radius of curvature of 80 mm. In other words,the cylindrical lens array 1105 b becomes a lens having dimensions of150 mm×32 mm×5 mm. The transverse direction and the meridional plane aredisposed in parallel. Further, the 16 cylindrical lenses are disposedsuch that the laser beam divided into 16 parts by the cylindrical lensarray 1105 a is made incident to the 16 cylindrical lenses of thecylindrical lens array 1105 b in the proportions of one to one. Notethat, for simplicity, two groups of four cylindrical lenses each areshown in FIG. 1.

[0074] Continuing, a cylindrical lens 1106 is placed in a position thatis 1600 mm behind the cylindrical lens array 1105 b. The cylindricallens 1106 is a planoconvex cylindrical lens having a length of 550 mm, awidth of 60 mm, a thickness of 20 mm, and a radius of curvature equal to486 mm. The incidence surface for the laser beam is a planar surface.The transverse direction and the meridional plane are disposed inparallel. The laser beam is thus converted once into a linear shape beamhaving a width on the order of 2 mm at a planar surface disposed 1000 mmbehind the cylindrical lens 1106.

[0075] A doublet cylindrical lens 1108 is placed at a position 2050 mmbehind the cylindrical lens 1106. A 90° reflecting mirror 1107 is placedbetween the cylindrical lens 1106 and the doublet cylindrical lens 1108,and a stage 1109 on which a semiconductor film is disposed is set so asto be nearly parallel with a horizontal plane. The doublet cylindricallens 1108 is structured by two cylindrical lenses. If the surfaces froman incident surface to an exit surface are referred to as a firstsurface, a second surface. a third surface, and a fourth surface, thenthe radius of curvature of the first surface is 125 mm, the radius ofcurvature of the second surface is 77 mm, the radius of curvature of thethird surface is 97 mm, and the radius of curvature of the fourthsurface is 200 mm. A positive numeral used here indicates that thecenter of the radius of curvature is on the side that the laser beamexits, while a negative numeral indicates that the center of the radiusof curvature is on the side that the laser beam enters. The centerdistance between the first surface and the second surface is 10 mm, thecenter distance between the second surface and the third surface is 5.5mm, and the center distance between the third surface and the fourthsurface is 20 mm. The doublet cylindrical lens has a length of 1000 mm,a width of 70 mm, and a thickness of 35.5 mm. The transverse directionand the meridional plane are disposed in parallel. The stage 1109 isdisposed in a position approximately 238 mm behind the doubletcylindrical lens. The position of the stage 1109 must be determined withextreme precision. This is because the focus depth of the optical systemis only on the order of 0.5 mm. The complete optical system as discussedabove is defined by radius of curvature, and the numerical values aretaken for lenses that use a base material having a refraction indexequal to 1.4856. It is therefore needless to say that it is necessary toconsider corrections to the above numerical values if the base materialof the lenses has a different refraction index.

[0076] A substrate 1111 on which a semiconductor film is formed isplaced on the stage 1109. The stage 1109 is provided with slightcurvature having a concave cylindrical shape, with the radius ofcurvature equal to 40,000 mm. The center of the radius of curvature ison the side that the laser beam enters. and the curvature direction isparallel to the sagittal plane. The stage 1109 operates in a directionperpendicular to a linear shape beam 1110 (dashed line portions withinthe figure), and the laser beam is irradiated to the entire surface ofthe semiconductor film by continuing to irradiate the laser beam whilethe stage operates. A maximum height difference of 3 mm between thecenter of the substrate and the substrate edges can be formed inaccordance with the curvature provided by the stage 1109. It can thus beunderstood that the effect of imparting a larger curvature to the stagethan the focus depth of the linear shape beam (normally on the order of0.5 mm) is absolute. Further, substrates having a side length on theorder of 1 m, with a thickness on the order of 1 mm are extremely easyto bend, and the curvature is easy to impart provided that thedeformation is on the order of 3 mm. The deformation imparted to thesubstrate disappears after the substrate is removed from the stage afterlaser beam irradiation is completed.

[0077] Irradiation of the linear shape beam is performed while scanningthe stage 1109 in the direction of the arrow on the stage shown in FIG.1, for example. The energy density of the linear shape beam on thesemiconductor film, and the speed of the stage may be suitablydetermined by the operator at this point. Roughly speaking, the energydensity is within a range from 100 mJ/cm² to 1000 mJ/cm². If a stagespeed is selected appropriately for a range in which there is 90% orgreater overlap in the transverse direction of the linear shape beams,then there is a good possibility of performing uniform laser annealing.The optimal stage speed depends upon the frequency of the laseroscillator, and may be considered to be proportional to the frequency.The example of FIG. 1 shows the movement of the stage with respect tothe linear shape beam, but the stage may also be fixed, and the linearshape laser beam may be moved. It is acceptable oscillation, providedthat the movement is performed in a relative manner. Further, if acontinuous oscillation laser is used, then emission may be performedwhile moving the stage relative to the laser beam at a speed on theorder of 0.5 to 2000 cm/s.

[0078] The laser annealing process is thus completed. A plurality ofsubstrates can be processed by repeating the aforementioned steps. Anactive matrix liquid crystal display, for example, can be manufacturedby utilizing the substrate. Manufacturing may be performed by theoperator in accordance with a known method, for example.

[0079] A linear shape beam that has an extremely uniform energydistribution and a length that exceeds 500 mm can be formed by utilizingthe present invention, and therefore the present invention is suitablefor being incorporated into a mass production line. Laser oscillatorshaving high output, and which are capable of ensuring sufficient energydensity when a linear shape beam is expanded in the longitudinaldirection, are used. The necessary output depends on the width of thelinear shape beam in the transverse direction and the laser beamwavelength, but is preferable to have an energy greater than or equal to1 J per pulse.

[0080] Although an excimer laser is used for the laser oscillator in theaforementioned example, similar high output can also be obtained byusing the higher harmonic waves of YAG lasers or glass lasers inaddition to the excimer laser. These lasers are preferable becausesilicon films have good absorption of the laser beam energy of suchlasers. In addition, lasers such as YVO₄ lasers (higher harmonic waves),YLF lasers (higher harmonic waves), and Ar lasers may be used as laseroscillators suitable for crystallizing silicon films. The laser beamwavelength region for these laser oscillators is well absorbed bysilicon films.

[0081] A linear shape beam having an extremely uniform energydistribution can thus be formed with the present invention, andtherefore the physical properties of semiconductor films obtained byirradiation of this type of linear shape beam also become uniform.Dispersion in the electrical characteristics of TFTs manufactured usingthe semiconductor films is thus reduced, and good TFTs are obtained.

[0082] Note that, annealing through the use of a laser beam is performedin embodiment 1 in a state in which the semiconductor film is formedover the entire substrate. However, laser annealing may also beperformed after first patterning the semiconductor film into a desiredshape.

[0083] Embodiment 2

[0084] The energy distribution of laser beams in an irradiation surfaceare compared in embodiment 2 for cases in which the present invention isapplied, and cases in which the present invention is not applied.

[0085] It is understood from Eq. (1) that f2/f1 is increased in order tomake the length L in the longitudinal direction of a linear shape laserbeam longer. (See FIG. 3 for each variable) It is also possible to makethe width d of cylindrical lenses contained in a cylindrical lens arraylarger. This is not preferable, however, because the number of laserbeam divisions is reduced, and therefore the uniformity of the energydistribution of the linear shape beam is damaged. Further, L becomeslarger if f2 is increased, but the distance between the lens and anirradiation surface increases, and therefore the footprint becomeslarger, which is uneconomical. Consequently, it can be understood thatit is most preferable to reduce f1 in order to increase the length L inthe longitudinal direction of the linear shape beam.

[0086] A simulation of the energy distribution in the irradiationsurface when using the optical system shown by FIG. 1 has beenperformed. A detailed explanation of the optical system can be found inembodiment 1. The beam expander 1102 is structured by a planoconcavelens having a first face curvature of 220 mm and a thickness of 7 mm,and by a planoconvex lens having a second face curvature of 400 mm, anda thickness of 12 mm, which is placed at a distance of 353 mm from theplanoconcave lens. The cylindrical lens array 1103 has been disposed ata distance of 50 mm from the beam expander 1102. The curvature of theother lenses, and the distances between lenses has been as stated inembodiment 1. Note that, the structure of the optical system shown byFIG. 1 differs from the structure of the optical system shown by FIG. 2.However, a laser beam, which is similar in shape to the laser beam ofFIG. 1, can be obtained on an irradiation surface in accordance with thestructure of FIG. 2.

[0087] If the radius of curvature of the cylindrical lens array 1103 istaken as 14 mm in an optical system having an optical path length ofapproximately 5 m from the laser oscillator shown in FIG. 1 to theirradiation surface, then the size of the linear shape beam formed onthe irradiation surface will become 300 mm×0.4 mm. An example of thesimulation results for the energy distribution of this linear shape beamis shown in FIG. 4A. The vertical represents the linear direction of thelaser beam, and the horizontal axis represents the transverse directionof the laser beam. The vertical axis applies a scale different from thatfor the horizontal axis in order to make the results easier to see.Hereafter, similar figures are shown in accordance with the same rules.The shading within the figures corresponds to the energy density of thelaser beam. From FIG. 4A, it can be seen that an extremely uniformenergy distribution can be obtained. However, when the radius ofcurvature of the cylindrical lens array 1103 (a cylindrical lens array1203 if the optical system structure of FIG. 2 is used) is simplyreduced to a value of 4 mm in this optical system, and the length in thelongitudinal direction of the linear shape beam on the irradiationsurface is increased to a length on the order of 1000 mm, the uniformityof the energy distribution of the laser beam in the longitudinaldirection of the linear shape beam drops remarkably. (See FIG. 4B) Notethat the length of the linear shape beam in the transverse directionremains at 0.4 mm.

[0088] The applicants of the present invention consider that the energyuniformity is adversely affected by the fact that the angle at which thelaser beam expands becomes very large, which is due to the length in thelongitudinal direction of the linear shape beam expanding by a largeamount. It has been supposed that the focus position in the vicinity ofthe center of the linear shape beam differ from the focus positions atboth ends of the linear shape beam, in the longitudinal direction. Usingoptical design software, the shape of the substrate in the irradiationsurface has been changed from planar to a shape having cylindricalcurvature, thus assuming a shape in which the height of the center ofthe substrate differs from the height at both edges of the substrate.The simulation was again performed, and the uniformity of the energydistribution of the linear shape beam increased greatly.

[0089] Simulation results for a case adding curvature to the substrateand then forming a 1000 mm×0.4 mm linear shape beam are shown in FIG. 6.It can be seen that the energy distribution of the linear shape beam isconsiderably improved compared with FIG. 4B.

[0090] The effectiveness of the present invention is illustrated fromthe aforementioned simulation results.

[0091] Embodiment 3

[0092] An example is given in embodiment 3 of an optical system thatdiffers from the optical systems discussed in embodiment 1 andembodiment 2. Specifically, an explanation is made regarding just howmuch curvature must be provided to a semiconductor film when the lengthof a linear shape beam is changed.

[0093] The length of the linear shape beam can be changed in the opticalsystem shown in FIG. 1 by changing the focal distance of the cylindricallens array 1103. An example of specific numerical values is as follows:if the length of the linear shape beam is 300 mm, the radius ofcurvature of the cylindrical lens array 1103 may be set to 14 mm, and ifthe length of the linear shape beam is 600 mm, then the radius ofcurvature may be set to 7 mm. In other words, it can be considered thatthere is an inversely proportional relationship between the radius ofcurvature and the linear beam length.

[0094] Simulation results for the energy distribution of a linear shapebeam on an irradiation surface when the linear shape beam length is 600mm are shown in FIGS. 7A and 7B. Shown in FIG. 7A are simulation resultswhen there is no semiconductor film curvature, namely when thesemiconductor film is planar. Results are shown in FIG. 7B for asimulation run wherein curvature is imparted to the semiconductor film,and the radius of curvature given to the semiconductor film has been40,000 mm, the same as that shown in embodiment 1. It can be seen thatthe uniformity of the energy distribution of the linear shape beamincreases greatly by imparting curvature to the semiconductor film.

[0095] Simulation results for the energy distribution of a linear shapebeam on an irradiation surface when the linear shape beam length is 300mm are shown in FIGS. 8A and 8B. Shown in FIG. 8A are simulation resultswhen there is no semiconductor film curvature, namely when thesemiconductor film is planar. Results are shown in FIG. 8B for asimulation run wherein curvature is imparted to the semiconductor film,and the radius of curvature given to the semiconductor film has been40,000 mm, the same as that shown in embodiment 1. It can be seen thatthere is no advantage difference between FIGS. 5A and 5B, and that thepresent invention may be preferably adapted to relatively long linearshape beams.

[0096] The optical system for the linear shape beam having a length of600 mm illustrated by embodiment 3 may be applied when the substratesize is 600 mm×720 mm. The radius of curvature given to the substrate atthis time is set to 40,000 mm, similar to that shown in embodiment 1.

[0097] Linear annealing of a semiconductor film is performed, forexample, by utilizing the optical system shown by embodiment 3 inaccordance with the method shown by embodiment 1. The active matrixliquid crystal display, for example, can be manufactured by utilizingthe semiconductor film. Manufacture may be performed in accordance witha method predetermined by the operator.

[0098] Embodiment 4

[0099] An example of an optical system that differs from the opticalsystems described in embodiments 1 to 3 is given in embodiment 4.Specifically, an explanation is made regarding just how much curvaturemust be provided to a semiconductor film when the optical path length ofthe optical system is changed.

[0100] In order to change only the optical path length of the opticalsystem without changing the length of a linear shape beam, the value ofthe focal length f1 of a cylindrical lens array 1301 and the value ofthe focal length f2 of a cylindrical lens array 1302 in FIG. 3 may bechanged without changing the ratio between f1 and f2. In particular, thefocal length f2 is almost equal to the distance between the cylindricallens array 1302 and the irradiation surface, and therefore has a strongcorrelation to the optical path length of the optical system.

[0101] In embodiment 1, the cylindrical lens 1104 corresponds to acylindrical lens possessing the focal length f2. The focal length f2 ofthe cylindrical lens 1104 is on the order of 4400 mm. By changing f2without changing the linear beam length, namely changing f2 withoutchanging the focal length ratio between f1 and f2 (note that f1 alsochanges in order to keep the same ratio between f1 and f2), andinvestigating the energy distribution in the irradiation surface bysimulation using the optical system shown in embodiment 1, a curvatureradius range that the substrate must possess in order to obtain auniform energy distribution is determined. The curvature radius rangethus obtained that the substrate must possess with respect to f2 isshown in Table 1. and a graph of the correlation between f2 and thecurvature radius range that the substrate must possess is shown in FIG.9. Note that only optimal values are recorded when the focal length f2is equal to 2200 mm and 3600 mm because the curvature radius range thatthe substrate must possess is relatively narrow.

[0102] Table 1

[0103] Further, two equations Eq. 2 and Eq. 3 shown in FIG. 9 areapproximate equations for the minimum value, and the maximum value,respectively, of the radius of curvature that the substrate must possesswhen f2 is changed:

[0104] [Eq. 2]

[0105] [Eq. 3]

[0106] In other words, a laser beam having a uniform energy distributionon the substrate surface can be obtained provided that the radius ofcurvature of the substrate with respect to f2 falls within the range ofthe two equations.

[0107]FIG. 9 has values for the focal length f2 of the cylindrical lens1104 on its vertical axis, and values for the radius of curvature thatthe substrate must possess on its horizontal axis. The cylindrical lens1104 can be regarded as a condenser lens for making the energydistribution uniform in the longitudinal direction of the linear shapebeam due to its function. From the graph of FIG. 9, it can be seen thatthe radius of curvature, which the substrate must possess, increasesalong with increasing f2. When f2 equals 8800 mm, namely when f2 hastwice the value of the optical system shown in embodiment 1, the optimalvalue for the radius of curvature becomes 150,000 mm. However, when thevalue becomes this large, the radius of curvature is infinite. Theenergy distribution of the linear shape beam for a planar substrate isalmost the same as the energy distribution for the linear shape beam fora case in which the radius of curvature is equal to 150,000 mm. At thispoint, f2 is 8800 mm, and therefore the optical path length of theoptical system is on the order of 10 m.

[0108] If the focal length f2 is equal to 6600 mm, for example, then theenergy distribution of the linear shape beam becomes most uniform whenthe radius of curvature is on the order of 60,000 mm. In this case,there is a clear advantage over planar substrates, and this shows arange in which the present invention is effective. Similarly, the radiusof curvature may be set to 50,000 mm when the focal length f2 is equalto 5500 mm, the radius of curvature may be set to 20,000 mm for cases inwhich the focal length f2 is equal to 3600 mm, and the radius ofcurvature may be set to 9000 mm if the focal length f2 is equal to 2200mm. From the above discussion, the shape change of the linear shape beambecomes larger, and the energy distribution loses uniformity, if thefocal length f2 is made shorter. Further, the radius of curvatureimparted to the substrate becomes smaller, and the load on the substrateincreases. The difference in height between the center and edge portionsof a substrate having a width of 1 m is 14 mm if the substrate is bentto a 9000 mm radius of curvature. The radius of curvature imparted tothe substrate does change, of course, depending upon the substratematerial, but this radius of curvature is in the vicinity of the limitable to be imparted to the glass substrates generally in use at present.

[0109] Laser annealing of a semiconductor film is performed inaccordance with the method shown by embodiment 1, for example, utilizingthe optical system of embodiment 4. An active matrix liquid crystaldisplay, for example, can be manufactured by utilizing the semiconductorfilm. Manufacturing may be performed in accordance with a methodpredetermined by the operator.

[0110] Embodiment 5

[0111] Another method of manufacturing a semiconductor film is shown inembodiment 5. The characteristics of the semiconductor film shown byembodiment 5 are increased remarkably if the semiconductor film shown byembodiment 5 undergoes laser annealing. A method of manufacturing apolycrystalline silicon film is discussed in embodiment 5.

[0112] First, a silicon oxide film having a thickness of 200 nm, and anamorphous silicon film having a thickness of 50 nm, are formed in orderon one surface of a glass substrate. Methods such as plasma CVD andsputtering may be performed as the film forming method. The amorphoussilicon film is crystallized next by thermal annealing. Thermalannealing is a heat treatment for the amorphous silicon film, forexample at 600° C. in a nitrogen atmosphere for a length of time on theorder of 24 hours. Alternatively, the amorphous silicon film may becrystallized by the RTA method. Further, crystallization of theamorphous silicon film may also be performed by the method disclosed inJapanese Patent Application Laid-open No. Hei 7-130652. An example ofusing this method is explained below.

[0113] First, a base film (for example, a 200 nm thick silicon oxidefilm) is formed on one surface of a glass substrate, and then anamorphous semiconductor film having a thickness of 20 to 100 nm isformed. Films such as amorphous silicon films, amorphous silicongermanium (a-SiGe) films, amorphous silicon carbide (a-SiC) films, andamorphous silicon tin (a-SiSn) films can be applied to the amorphoussemiconductor film. These amorphous semiconductor films may be formedsuch that the amount of hydrogen contained within the amorphoussemiconductor film is on the order of 0.1 to 40% of the total number ofatoms. For example, an amorphous silicon film is formed having athickness of 55 nm. A layer containing a metallic element is then formedby a spin coating method in which a liquid solution containing 10 ppm byweight of a metallic element is applied by a spinner while the substrateis rotating. Metallic elements such as nickel (Ni), germanium (Ge), iron(Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum (Pt),copper (Cu), and gold (Au) may be used as the metallic element. Inaddition to spin coating, the layer containing the metallic element mayalso be formed by printing, spraying, bar coating, sputtering, andvacuum evaporation methods, and is formed having a thickness of 1 to 5nm.

[0114] For a crystallization process, it is preferable to first performheat treatment at 400 to 500° C. for a period on the order of 1 hour ina nitrogen atmosphere, thus reducing the amount of hydrogen containedwithin the amorphous silicon film to a level equal to or less than 5% ofthe total number of atoms contained within the amorphous silicon film.It is not necessary to perform that heat treatment for cases in whichthe amount of hydrogen contained within the amorphous silicon film afterfilm formation is already equal to or less than 5%. Heat treatment isthen performed within a nitrogen atmosphere at a temperature of 550 to600° C. for 1 to 8 hours using an annealing furnace. A polycrystallinesemiconductor film composed of a polycrystalline silicon film can thusbe obtained by the aforementioned processes. However, if thepolycrystalline semiconductor film manufactured by thermal annealing isobserved by using an optical microscope, localized amorphous regionsremaining within the film may be seen. Similarly, amorphous componentspossessing a broad peak at 480 cm⁻¹ can be observed by Ramanspectroscopy for cases in which the amorphous regions remain. Processingthe polycrystalline semiconductor film by using the laser annealingmethod disclosed in embodiment 5 after thermal annealing, thusincreasing crystallinity, can therefore be applied as an effectivemeans. The crystallization process may also be performed by the RTAmethod.

[0115] The crystalline semiconductor shown in the manufacturing examplein embodiment 5 has an absorption coefficient wavelength dependence,which differs from that of an amorphous semiconductor film. Inparticular, the difference between the two is large in the visible lightregion. For example, the absorption coefficient of the crystallinesilicon film for the wavelengths of the second harmonic wave of a YAGlaser or the second harmonic wave of a glass laser is an order ofmagnitude smaller than that of the amorphous silicon film. Therefore, itis preferable that the energy density of the linear shape beam be madeto differ between amorphous semiconductor films and crystallinesemiconductor films when a visible light laser is used in the laseroscillator. On the other hand, if an excimer laser, the third harmonicwave of a YAG laser, or the like is used in the laser oscillator, thenthere is almost no difference in the optimal linear shape beam energydensity between both film types during laser annealing because theabsorption coefficient is nearly the same for amorphous silicon filmsand crystalline silicon films.

[0116] Embodiment 6

[0117] In this embodiment, a method of manufacturing an active matrixsubstrate will be described with reference to FIGS. 10A to 13. Asubstrate on which a CMOS circuit, a driver circuit, and a pixel portionhaving a TFT pixel and a holding capacity are formed together is calledactive matrix substrate for convenience.

[0118] First, a substrate 350 formed of glass such as bariumborosilicate glass and aluminum borosilicate glass is used in thisexample. The substrate 350 may be a quartz substrate, a siliconsubstrate or a metal substrate or stainless substrate, which has aninsulating film on the surface. The substrate 350 may be a plasticsubstrate having heat resistance, which withstands a processingtemperature in this embodiment.

[0119] Next, a primary film 351 having an insulating film such assilicon oxide film, silicon nitride film, and a silicon oxide nitridefilm is formed on the substrate 350. In this embodiment, a two-layerstructure is used for the primary film 351. However, a structure may beused where a single layer film, which is the insulating film itself, orat least two layers are stacked. As a first layer of the primary film351, a silicon oxide nitride film 351 a is formed 10 to 200 nm(preferably 50 to 100 nm) thick by using SiH₄, NH₃ and N₂O as a reactiongas in accordance with the plasma CVD method. In this embodiment, asilicon oxide nitride film 351 a (compositional ratio: Si=32%, O=27%,N=24% and H=17%) was formed 50 nm thick. Next, as a second layer of theprimary film 351, a silicon oxide nitride film 351 b is formed 50 to 200nm (preferably 100 to 150 nm) thick by using SiH₄ and N₂O as a reactiongas in accordance with the plasma CVD method. In this embodiment, asilicon oxide nitride film 351 b (compositional ratio: Si=32%, O=59%,N=7% and H=2%) is formed 100 nm thick.

[0120] Next, semiconductor layers 402 to 406 are formed on the primaryfilm. First, semiconductor film 352 having an amorphous structure isformed 25 to 80 nm thick (preferably 30 to 60 nm) by a publicly knownmethod (such as the sputtering method, LPCVD method and plasma CVDmethod). Crystallization is performed to the semiconductor film by thelaser crystallization method using the present invention. When acrystalline semiconductor film is produced in accordance with the lasercrystallization method, the pulse type or the continuous light-emittingtype of solid laser, gaseous laser or metal laser is preferable to beused. As above mentioned solid laser, the pulse type or the continuouslight-emitting type of YAG laser, YVO₄ laser, YLF laser, YAlO₃ laser,glass laser, ruby laser or Ti: sapphire laser may be applied. As abovementioned gas laser, the pulse type or the continuous light-emittingtype of excimer laser, Ar laser, Kr laser and CO₂ laser etc. As abovementioned metal laser. helium cadmium laser, copper vapor laser and goldvapor laser can be applied. When these types of laser are used, a methodis preferable whereby laser beam emitted from a laser oscillation isgathered by an optical system and is irradiated to a semiconductor film.The condition of the crystallization may be selected by the practitioneras necessary. However, when excimer laser is used, the pulse frequencyis 300 Hz and the laser energy density is 100 to 1200 mJ/cm², preferably100 to 700 mJ/cm² (typically 200 to 500 mJ/cm²). Preferably, when YAGlaser is used, the second harmonic is used, and the pulse frequency is 1to 10000 Hz, preferably 1 to 300 Hz. The laser energy density is 200 to1800 mJ/cm², preferably 300 to 1000 mJ/cm² (typically 350 to 500mJ/cm²). Then laser light gathered linearly of 10 to 1000 μm wide, or400 μm wide in this embodiment. is irradiated all over the surface ofthe substrate. The overlap percentage of the linear beams may be 50 to98%. When continuous laser oscillation is used, the energy densitythereof must be the order of 0.01 to 100 MW/cm² (preferably 0.1 to 10MW/cm²). The stage is moved relatively with respect to laser light at aspeed of the order of 0.5 to 2000 cm/s for the irradiation of the laserlight to form the crystal semiconductor film.

[0121] Further, the crystallization can be carried out by combininganother known crystallization method (such as RTA method, using thermalcrystallization annealing using an annealing furnace and thermalcrystallization annealing using a metal element promotingcrystallization) with laser crystallization method.

[0122] Patterning is performed on the obtained crystalline semiconductorfilm in a desired form in order to form the semiconductor lasers 402 to406. The semiconductor film may be an amorphous semiconductor film, afine crystal semiconductor film 352 or a crystalline semiconductor film.Alternatively, the semiconductor film 352 may be a compoundsemiconductor film having an amorphous structure such as an amorphoussilicon germanium film. In this embodiment, plasma CVD method is used toform an amorphous silicon film 55 nm thick. The semiconductor film iscrystallized to form the crystal silicon film by excimer laser. Thesemiconductor layers 402 to 406 are formed by performing patterningprocessing thereon by using the photolithography method.

[0123] After the semiconductor layers 402 to 406 are formed, a smallamount of impurity element (boron or phosphorus) may be doped in orderto control a threshold value of the TFT.

[0124] Next, a gate insulating film 407 covering the semiconductorlayers 402 to 406 is formed. The gate insulating film 407 is formed byusing insulating film 40 to 150 nm thick containing silicon inaccordance with plasma CVD method or sputtering method. In thisembodiment, a silicon oxide nitride film (compositional ratio: Si=32%,O=59%, N=7% and H=2%) 110 nm thick is formed in accordance with theplasma CVD method. Notably, the gate insulating film is not limited tothe silicon oxide nitride film but an insulating film containing othersilicon may be used as a single layer or as a laminated pad.

[0125] When a silicon oxide film is used, it is formed by mixingTetraethyl Orthosilicate (TEOS) and O₂ by plasma CVD method, which isdischarged under a condition with reaction pressure of 40 Pa, asubstrate temperature of 300 to 400° C. and high frequency (13.56 MHz)power density of 0.5 to 0.8 W/cm². Thermal annealing at 400 to 500° C.thereafter can give good characteristics to the silicon oxide filmproduced in this way as a gate insulating film.

[0126] Next, a first conductive film 408, which is 20 to 100 nm thick,and a second conductive film 409, which is 100 to 400 nm thick, isstacked on the gate insulating film 407. In this embodiment, the firstconductive film 408 formed by a TaN film 30 nm thick and the secondconductive film 409 formed by a W film 370 nm thick are stacked. The TaNfilm is formed by using Ta target to perform sputtering in an atmospherecontaining nitrogen. The W film is formed by using W target to performsputtering. Alternatively, it can be formed by thermal CVD method using6 tungsten fluorides (WF₆). In both cases, the use of the gate electrodeneeds low resistance. Therefore, the resistivity of the W film isdesirably 20 μΩcm or below. The low resistance of the W film can beachieved by increasing the size of the crystal grains. However, when theW film contains a large amount of impurity element such as oxygen, thecrystallization is inhibited, which raises the resistance. Accordingly,in this embodiment, the W film is formed by the sputtering method usinghigh purity (purity of 99.9999%) W target and by taking the preventionof intrusion of impurity from a vapor phase during the film forming intospecial consideration. Thus, the resistivity of 9 to 20 μΩcm can beachieved.

[0127] While, in this embodiment, the first conductive film 408 is TaNand the second conductive film 409 is W, they are not limited inparticular. Both of them can be formed by an element selected from Ta,W, Ti, Mo, Al, Cu, Cr and Nd or an alloy material or a compound materialmainly containing the element. Alternatively, a semiconductor film. suchas a polycrystalline silicon film to which an impurity element such asphosphorus is doped, can be used. An AgPdCu alloy may be used. Acombination of the first conductive film formed by a tantalum (Ta) filmand the second conductive film formed by a W film, a combination of thefirst conductive film formed by a titan nitride (TiN) and the secondconductive film formed by a W film, a combination of the firstconductive film formed by a tantalum nitride (TaN) film and the secondconductive film formed by an Al film, or a combination of the firstconductive film formed by a tantalum nitride (TaN) film and the secondconductive film formed by a Cu film is possible.

[0128] Next, resist masks 410 to 415 using photolithography method arcformed, and first etching processing is performed thereon in order toform electrodes and wirings. The first etching processing is performedunder first and second etching conditions (FIG. 10C). The first etchingcondition in this embodiment is to use Inductively Coupled Plasma (ICP)etching and to use CF₄ and Cl₂ and O₂ as an etching gas, whose amount ofgases are 25/25/10 (sccm), respectively. 500 W of RF (13.56 MHz) powerwas supplied to a coil type electrode by 1 Pa pressure in order togenerate plasma and then to perform etching. Here, a dry etching deviceusing ICP (Model E645-□ICP) manufactured by Matsushita ElectricIndustrial Co., Ltd was used. 150 W of RF (13.56 MHz) power was alsosupplied to a substrate side (test sample stage) and substantiallynegative self-bias voltage was applied. The W film was etched under thefirst etching condition so as to obtain the end of the first conductivelayer in a tapered form.

[0129] After that, the first etching condition is shifted to the secondetching condition without removing the resist masks 410 to 415. Then,CF₄ and Cl₂ are used as etching gases. The ratio of the amounts offlowing gasses is 30/30 (sccm). 500 W of RF (13.56 MHz) power issupplied to a coil type electrode by 1 Pa pressure in order to generateplasma and then to perform etching for amount 30 seconds. 20 W of RF(13.56 MHz) power is also supplied to a substrate side (test samplestage) and substantially negative self-bias voltage is applied. Underthe second etching condition where CF₄ and Cl₂ are mixed, both W filmand TaN film were etched to the same degree. In order to etch withoutleaving a residue on the gate insulating film, the etching time may beincreased 10 to 20% more.

[0130] In the first etching processing, when the form of the resist maskis appropriate, the form of the ends of the first and the secondconductive layers are in the tapered form due to the effect of the biasvoltage applied to the substrate side. The angle of the tapered portionis 15 to 45°. Thus, conductive layers 417 to 422 in a first form areformed which include the first conductive layers and the secondconductive layers (first conductive layers 417 a to 422 a and secondconductive layer 417 b to 422 b) through the first etching processing.In a gate insulating film 416, an area not covered by the firstconductive layers 417 to 422 is etched by about 20 to 50 nm so as toform a thinner area.

[0131] Next, second etching processing is performed without removingresist masks (FIG. 10D). Here, CF₄, Cl₂ and O₂ are used to etch the Wfilm selectively. Then, second conductive layers 428 b to 433 b areformed by the second etching processing. On the other hand, the firstconductive layers 417 a to 422 a are not etched very much, andconductive layers 428 to 433 in the second form are formed.

[0132] First doping processing is performed without removing resistmasks and low density of impurity element, which gives n-type to thesemiconductor layer. is added. The doping processing may be performed inaccordance with the ion-doping method or the ion-implanting method. Theion doping method is performed under a condition in the dose of 1×10¹³to 5×10¹⁴/cm² and the accelerating voltage of 40 to 80 keV. In thisembodiment, the ion doping method is performed under a condition in thedose of 1.5×10¹³/cm² and the accelerating voltage of 60 keV. The n-typedoping impurity element may be Group 15 elements. typically phosphorus(P) or arsenic (As). Here, phosphorus (P) is used. In this case. theconductive layers 428 to 433 function as masks for the n-type dopingimpurity element. Therefore, impurity areas 423 to 427 are formed in theself-alignment manner. An n-type doping impurity element in the densityrange of 1×10¹⁸ to 1×10²⁰/cm⁻¹ is added to the impurity areas 423 to427.

[0133] When resist masks are removed, new resist masks 434 a to 434 care formed. Then. second doping processing is performed by using higheraccelerating voltage than that used in the first doping processing. Theion doping method is performed under a condition in the dose of 1×10¹³to 1×10¹⁵/cm² and the accelerating voltage of 60 to 120 keV. In thedoping processing, the second conductive layers 428 b to 432 b are usedas masks against the impurity element. Doping is performed such that theimpurity element can be added to the semiconductor layer at the bottomof the tapered portion of the first conductive layer. Then, third dopingprocessing is performed by having lower accelerating voltage than thatin the second doping processing to obtain a condition shown in FIG. 11A.The ion doping method is performed under a condition in the dose of1×10¹⁵ to 1×10¹⁷/cm² and the accelerating voltage of 50 to 100 keV.Through the second doping processing and the third doping processing, ann-type doping impurity element in the density range of 1×10¹⁸ to5×10¹⁹/cm³ is added to the low density impurity areas 436, 442 and 448,which overlap with the first conductive layer. An n-type doping impurityelement in the density range of 1×10¹⁹ to 5×10²¹/cm³ is added to thehigh density impurity areas 435, 441, 444 and 447.

[0134] With proper accelerating voltage, the low density impurity areaand the high density impurity area can be formed by performing thesecond doping processing and the third doping processing once.

[0135] Next, after removing resist masks, new resist masks 450 a to 450c are formed to perform the fourth doping processing. Through the fourthdoping processing, impurity areas 453 to 456, 459 and 460, to which animpurity element doping a conductive type opposite to the one conductivetype is added, in a semiconductor layer, which is an active layer of ap-channel type TFT. Second conductive layers 428 a to 432 a are used asmask against the impurity element, and the impurity element givingp-type is added so as to form impurity areas in the self-alignmentmanner. In this embodiment, the impurity areas 453 to 456. 459 and 460are formed by applying ion-doping method using diborane (B₂H₆) (FIG.11B). During the fourth doping processing, the semiconductor layerforming the n-channel TFT is covered by resist masks 450 a to 450 c.Thorough the first to the third doping processing, phosphorus ofdifferent densities is added to each of the impurity areas 438 and 439.Doping processing is performed such that the density of p-type dopingimpurity element can be 1×10¹⁹ to 5×10²¹ atoms/cm³ in both areas. Thus,no problems are caused when they function as the source region and thedrain region of the p-channel TFT.

[0136] Impurity areas are formed in the semiconductor layers,respectively, through the processes above.

[0137] Next, the resist masks 450 a to 450 c are removed and a firstinterlayer insulating film 461 is formed thereon. The first interlayerinsulating film 461 may be an insulating film 100 to 200 nm thickcontaining silicon, which is formed by plasma CVD method or sputteringmethod. In this embodiment, silicon oxide nitride 150 nm thick is formedby plasma CVD method. The first interlayer insulating film 461 is notlimited to the silicon oxide nitride film but may be the otherinsulating film containing silicon in a single layer or in a laminatedpad.

[0138] Next, as shown in FIG. 11C, heating processing is performed torecover the crystalline characteristic of the semiconductor layers andto activate the impurity element added to each of the semiconductorlayer. The heating processing is performed by thermal annealing methodusing an annealing furnace. The thermal annealing method may beperformed in an atmosphere of nitrogen with the oxygen density of 1 ppmor below. preferably 0.1 ppm or below. at 400 to 700° C., typically at500 to 550° C. In this embodiment, the activation processing isperformed through thermal processing at 550° C. for four hours. Inaddition to the thermal annealing method, laser annealing method orrapid thermal annealing method (RTA method) may be applied. When thelaser annealing method is used to the large size substrate such as600×720 mm, the laser irradiation device disclosed in the presentinvention is preferable to be used. The types of the continuous or thepulse oscillations of solid laser, gaseous laser, or metal laser arepreferable to be used as a laser. When continuous laser oscillation isused, the energy density thereof must be the order of 0.01 to 100 MW/cm²(preferably 0.01 to 10 MW/cm²). The substrate is moved relatively withrespect to laser light at a speed of the order of 0.5 to 2000 cm/s forthe irradiation of the laser light. When excimer laser is used, thepulse frequency is 300 Hz and the laser energy density is 50 to 1000mJ/cm², (typically 50 to 700 mJ/cm²). The overlap percentage of thelinear beams may be 50 to 98%.

[0139] Alternatively, the heating processing may be performed before thefirst interlayer insulating film is formed. However, when a wiringmaterial in use is sensitive to heat, the activation processing ispreferably performed after forming an interlayer insulating film(insulating film mainly containing silicon such as silicon nitride film)for protecting the wirings like this embodiment.

[0140] After the heating processing (thermal processing at 300 to 550°C. for 1 to 12 hours) is performed, hydrogenation can be performed. Thisprocess terminates the dangling bond of the semiconductor layer withhydrogen contained in the first interlayer insulating film 461. Thesemiconductor layer can be hydrogenated regardless of the existence ofthe first interlayer insulating film. Alternatively, the hydrogenationmay be plasma hydrogenation (using hydrogen excited by plasma) orheating processing in an atmosphere containing 3 to 100% of hydrogen at300 to 450° C. for 1 to 12 hours.

[0141] When laser annealing method is used for the activationprocessing, laser light such as excimer laser and YAG laser is desirablyirradiated after the hydrogenation is performed.

[0142] Next, a second interlayer insulating film 462 formed by anon-organic insulating material or an organic insulating material isformed on the first interlayer insulating film 461. In this embodiment,an acrylic resin film 1.6 μm thick is formed, whose viscosity is 10 to1000 cp, preferably 40 to 200 cp and which has depressions andprojections formed on the surface.

[0143] In this embodiment, in order to prevent mirror reflection, asecond interlayer insulating film 462 having projections and depressionson the surface is formed. Thus, the projections and depressions areformed on the surface of the pixel electrode. In order to obtain aneffect of light dispersion by forming the depressions and projections onthe surface of the pixel electrode, a projecting portion may be formedunder the pixel electrode. In this case, the projecting portion can beformed by using the same mask for forming a TFT. Thus. the projectingportion can be formed without any increase in the number of steps. Theprojecting portion may be provided as necessary on the substrate in thepixel area except for wirings and the TFT portion. Accordingly,projections and depressions can be formed on the surface of the pixelelectrode along the projections and depressions formed on the surface ofan insulating film covering the projecting portion.

[0144] Alternatively, the second interlayer insulating film 462 may be afilm having a flattened surface. In this case, after the pixel electrodeis formed, projections and depressions are formed on the surface byperforming an added process such as publicly known sand-blast method andetching method. Preferably, by preventing mirror reflection and bydispersing reflected light, the whiteness is increased.

[0145] Wirings 464 to 468 electrically connecting to impurity areas,respectively, are formed in a driver circuit 506. These wirings areformed by patterning a film laminating a Ti film 50 nm thick and analloy film (alloy film of Al and Ti) 500 nm thick. It is not limited tothe two-layer structure but may be a one-layer structure or a laminatepad including three or more layers. The materials of the wirings are notlimited to Al and Ti. For example, the wiring can be formed by formingAl or Cu on a TaN film and then by patterning the laminate film in whicha Ti film is formed (FIG. 12).

[0146] In a pixel portion 507, a pixel electrode 470, a gate wiring 469and a connecting electrode 468 are formed. Source wirings (a laminate oflayers 443 a and 443 b) are electrically connected with a TFT pixel bythe connecting electrode 468. The gate wiring 469 is electricallyconnected with a gate electrode of the TFT pixel. A pixel electrode 470is electrically connected with a drain region 442 of the TFT pixel.Furthermore, the pixel electrode 471 is electrically connected with asemiconductor layer 458 functioning as one electrode forming a storagecapacitor. Desirably, a material having excellent reflectivity such as afilm mainly containing Al or Ag or the laminate film is used for thepixel electrode 471.

[0147] In this way, the driver circuit 506 having a CMOS circuitincluding an n-channel TFT 501 and a p-channel TFT 502 and a n-channelTFT 503, and the pixel portion 507 having the TFT pixel 504 and thestorage capacitor 505 can be formed on the same substrate. Thus, anactive matrix substrate is completed.

[0148] The n-channel TFT 501 of the driver circuit 506 has a channelformed area 437, a low density impurity area 436 overlapping with thefirst conductive layer 428 a, which constructs a part of the gateelectrode, (GOLD area) and a high density impurity area 452 functioningas the source region or the drain region are implanted. The p-typechannel TFT 502 forming a CMOS circuit together with the n-channel TFT501, which are connected by an electrode 466, has a channel formed area440, a high density impurity area 454 functioning as the source regionor the drain region, and an impurity area 453 to which an n-type dopingimpurity element and a p-type doping impurity element are implanted. Then-channel TFT 503 has a channel formed area 443. a low density impurityarea 442 overlapping with the first conductive layer 430 a, whichconstructs a part of the gate electrode, (GOLD area), a high densityimpurity area 456 functioning as the source region or the drain region,and an impurity area 455 to which an n-type doping impurity element anda p-type doping impurity element are implanted.

[0149] The TFT pixel 504 of the pixel portion has a channel formed area446, a low density impurity area 445 formed outside of the gateelectrode (LDD region), a high density impurity area 458 functioning asthe source region or the drain region and an impurity region 457injected an n-type doping impurity element and a p-type doping impurityelement are implanted. An n-type doping impurity element and a p-typedoping impurity element are added to a semiconductor layer functioningas one electrode of the storage capacitor 505. The storage capacitor 505is formed by an electrode (a laminate of layers 432 a and 432 b) and asemiconductor layer by using the insulating film 416 as a dielectric.

[0150] The pixel structure in this embodiment is arranged such thatlight can be blocked in a space between pixel electrodes and the ends ofthe pixel electrodes can overlap with the source wiring without usingthe black matrix.

[0151]FIG. 13 shows a top view of the pixel portion of the active matrixsubstrate produced in this embodiment. The same reference numerals areused for the corresponding parts in FIGS. 10 to 13. A broken line A-A′in FIG. 12 corresponds to a sectional view taken along a broken lineA-A′ in FIG. 13. A broken line B-B′ in FIG. 12 corresponds to asectional view taken along a broken line B-B′ in FIG. 13.

[0152] It should be noted that this embodiment can be combined with anyone of Embodiments 1 to 5 freely.

[0153] Embodiment 7

[0154] This embodiment explains, below, a process to manufacture areflection type liquid crystal display device from the active matrixsubstrate made in Embodiment 6, using FIG. 14. Though there is nodescription about the present invention in this embodiment, the presentinvention may be applied to this embodiment, because this embodimentuses the active matrix substrate formed in Embodiment 6.

[0155] First, after obtaining an active matrix substrate in the state ofFIG. 12 according to Embodiment 6, an orientation film 567 is formed atleast on the pixel electrodes 470 on the active matrix substrate of FIG.12 and subjected to a rubbing process. Incidentally, in this embodiment,prior to forming an orientation film 567, an organic resin film such asan acryl resin film is patterned to form columnar spacers 572 in adesired position to support the substrates with spacing. Meanwhile,spherical spacers, in place of the columnar spacers, may be distributedover the entire surface of the substrate.

[0156] Then, a counter substrate 569 is prepared. Then, a coloring layer570, 571 and a planarizing film 573 are formed on a counter substrate569. A shade portion is formed by overlapping a red coloring layer 570and a blue coloring layer 571 together. Meanwhile, the shade portion maybe formed by partly overlapping a red coloring layer and a greencoloring layer.

[0157] In this embodiment is used a substrate shown in Embodiment 6.Accordingly, in FIG. 13 showing a top view of the pixel portion ofEmbodiment 6, there is a need to shade at least the gap between the gatewiring 469 and the pixel electrode 470, the gap between the gate wiring469 and the connecting electrode 468 and the gap between the connectingelectrode 468 and the pixel electrode 470. In this embodiment werebonded together the substrates by arranging the coloring layers so thatthe shading portion having a lamination of coloring layers is overlappedwith the to-be-shading portion.

[0158] In this manner, the gaps between the pixels are shaded by theshading portion having a lamination of coloring layers without forming ashading layer such as a black mask, thereby enabling to reduce thenumber of processes.

[0159] Then, a counter electrode 576 of a transparent conductive film isformed on the planarizing film 573 at least in the pixel portion. Anorientation film 574 is formed over the entire surface of the countersubstrate and subjected to a rubbing process.

[0160] Then, the active matrix substrate formed with the pixel portionand driver circuit and the counter substrate are bonded together by aseal member 568. The seal member 568 is mixed with filler so that thefiller and the columnar spacers bond together the two substrates throughan even spacing. Thereafter, a liquid crystal material 575 is pouredbetween the substrates, and completely sealed by a sealant (not shown).The liquid crystal material 575 may be a known liquid crystal material.In this manner, completed is a reflection type liquid crystal displaydevice shown in FIG. 14. If necessary, the active matrix substrate orcounter substrate is divided into a desired shape. Furthermore, apolarizing plate (not shown) is bonded only on the counter substrate.Then, an FPC is bonded by a known technique.

[0161] The liquid crystal display device manufactured as above usessemiconductor film. which is uniformly crystallized, by applying thelaser annealing of the present invention, and ensures enoughreliability. The liquid crystal display device can be used as a displayportion for an electronic appliance in various kinds.

[0162] Incidentally, this embodiment can be freely combined withEmbodiments 1 to 6.

[0163] Embodiment 8

[0164] This embodiment explains an example of a light-emitting devicemanufactured by using the present invention. Though there is nodescription about the present invention in this embodiment. the presentinvention may be applied to this embodiment. because this embodimentuses the active matrix substrate formed in Embodiment 6. In thisspecification. the light-emitting device refers, generally, to thedisplay panel having light-emitting elements formed on a substratesealed between the substrate and a cover member, and the display modulehaving an IC mounted on the display panel. Incidentally the lightemitting element has a layer including an organic compound thatelectroluminescence caused is obtained by applying an electric field(light-emitting layer), an anode and a cathode. Meanwhile, theelectroluminescence in organic compound includes the light emission(fluorescent light) upon returning from the singlet-excited state to theground state and the light emission (phosphorous light) upon returningfrom the triplet-excited state to the ground state, including any orboth of light emission.

[0165] All the layers that are provided between an anode and a cathodein a light emitting layer are an organic light emitting layer in thisspecification. Specifically, the organic light emitting layer includes alight emitting layer, a hole injection layer, an electron injectionlayer, a hole transporting layer, an electron transporting layer, etc. Abasic structure of a light emitting element is a laminate of an anode, alight emitting layer, and a cathode layered in this order. The basicstructure can be modified into a laminate of an anode, a hole injectionlayer, a light emitting layer, and a cathode layered in this order, or alaminate of an anode, a hole injection layer, a light emitting layer, anelectron transporting layer, and a cathode layered in this order.

[0166]FIG. 15 is a sectional view of a light-emitting device of thisembodiment. In FIG. 15, the switching TFT 603 provided on the substrate700 is formed by using the n-channel TFT 503 of FIG. 12. Consequently,concerning the explanation of the structure, it is satisfactory to referthe explanation on the n-channel TFT 503.

[0167] Incidentally, although this example is of a double gate structureformed with two channel regions, it is possible to use a single gatestructure formed with one channel region or a triple gate structureformed with three.

[0168] The driver circuit provided on the substrate 700 is formed byusing the CMOS circuit of FIG. 12. Consequently, concerning theexplanation of the structure, it is satisfactory to refer theexplanation on the n-channel TFT 501 and p-channel TFT 502.Incidentally, although this embodiment is of a single gate structure, itis possible to use a double gate structure or a triple gate structure.

[0169] Meanwhile, the wirings 701, 703 serve as source wirings of theCMOS circuit while the wiring 702 as a drain wiring. Meanwhile, a wiring704 serves as a wiring to electrically connect between the source wiring708 and the source region of the switching TFT while the wiring 705serves as a wiring to electrically connect between the drain wiring 709and the drain region of the switching TFT.

[0170] Incidentally, a current control TFT 604 is formed by using thep-channel TFT 502 of FIG. 12. Consequently, concerning the explanationof the structure, it is satisfactory to refer to the explanation on thep-channel TFT 502. Incidentally, although this embodiment is of a singlegate structure, it is possible to use a double gate structure or atriple gate structure.

[0171] Meanwhile, the wiring 706 is a source wiring of the currentcontrol TFT (corresponding to a current supply line) while the wiring707 is an electrode to be electrically connected to the pixel electrode711 by being overlaid a pixel electrode 711 of the current control TFT.

[0172] Meanwhile, 711 is a pixel electrode (anode of a light-emittingelement) formed by a transparent conductive film. As the transparentconductive film can be used a compound of indium oxide and tin oxide, acompound of indium oxide and zinc oxide, zinc oxide. tin oxide or indiumoxide, or otherwise may be used a transparent conductive film as aboveadded with gallium. The pixel electrode 711 is formed on a planarinterlayer insulating film 710 prior to forming the wirings. In thisembodiment, it is very important to planarize the step due to the TFT byusing a resin planarizing film 710. A light-emitting layer to be formedlater, because being extremely thin, possibly causes poor light emissiondue to the presence of a step. Accordingly, it is desired to provideplanarization prior to forming a pixel electrode so that alight-emitting layer can be formed as planar as possible.

[0173] After forming the pixel electrode 711, a bank 712 is formed asshown in FIG. 15. The bank 712 may be formed by patterning an insulatingfilm or organic resin film containing silicon having 100 to 400 nm.

[0174] Incidentally, because the bank 712 is an insulating film, cautionmust be paid to element electrostatic breakdown during deposition. Inthis embodiment added is a carbon particle or metal particle to aninsulating film as a material for the bank 712, thereby reducingresistivity and suppressing occurrence of static electricity. In such acase, the addition amount of carbon or metal particle may be adjusted toprovide a resistivity of 1×10⁶ to 1×10¹² Ωm (preferably 1×10⁸ to 1×10¹⁰Ωm).

[0175] A light-emitting layer 713 is formed on the pixel electrode 711.Incidentally, although FIG. 15 shows only one pixel, this embodimentseparately forms light-emitting layers correspondingly to the respectivecolors of R (red), G (green) and B (blue). Meanwhile, in this embodimentis formed a low molecular weight organic electroluminescent material bythe deposition process. Specifically, this is a lamination structurehaving a copper phthalocyanine (CuPc) film provided in a thickness of 20nm as a hole injecting layer and a tris-8-qyuinolinolato aluminumcomplex (Alq₃) film provided thereon in a thickness of 70 nm as alight-emitting layer. The color of emission light can be controlled byadding a fluorescent pigment, such as quinacridone, perylene or DCM1, toAlq₃.

[0176] However. the foregoing example is an example of organicelectroluminescent material to be used for a light-emitting layer andnot necessarily limited to this. It is satisfactory to form alight-emitting layer (layer for light emission and carrier movementtherefore) by freely combining a light-emitting layer, a chargetransporting layer and an electron injecting layer. For example,although in this embodiment was shown the example in which a lowmolecular weight organic electroluminescent material is used for alight-emitting layer, it is possible to use a middle molecular weightorganic electroluminescent material or high molecular weight organicelectroluminescent material. In this specification, middle molecularweight organic electroluminescent material is made an organic lightemitting material, which does not have the sublime, and which has 20 orless with 10 μm lengths chain molecular. As an example of using highmolecular organic light emitting material, the laminated pad can be made20 nm thick polythiophene (PEDOT) films is provided by spin coatingmethod as a hole injection layer, and 100 nm thickparaphenylene-vinylene (PPV) films thereon. The light emitting wavelength can be selected from red to blue by using π conjugated systemhigh molecular of PPV. The inorganic material such as a silicon carbidecan be used as an electron transporting layer and an electron injectionlayer. Known materials can be used to these organic light emitting layerand the inorganic light emitting layer.

[0177] Next, a cathode 714 of a conductive film is provided on thelight-emitting layer 713. In this embodiment, as the conductive film isused an alloy film of aluminum and lithium. A known MgAg film (alloyfilm of magnesium and silver) may be used. As the cathode material maybe used a conductive film of an element belonging to the periodic-tablegroup 1 or 2, or a conductive film added with such an element.

[0178] A light-emitting element 715 is completed at a time having formedup to the cathode 714. Incidentally, the light-emitting element 715herein refers to a diode formed with a pixel electrode (anode) 711, alight-emitting layer 713 and a cathode 714.

[0179] It is effective to provide a passivation film 716 in such amanner to completely cover the light-emitting element 715. Thepassivation film 716 is formed by an insulating film including a carbonfilm, a silicon nitride film or a silicon nitride oxide film, and usedis an insulating film in a single layer or a combined lamination.

[0180] In such a case, it is preferred to use a film favorable incoverage as a passivation film. It is effective to use a carbon film,particularly DLC (diamond-like carbon) film. The DLC film, capable ofbeing deposited in a temperature range of from room temperature to 100°C. or less, can be easily deposited over the light-emitting layer 713low in heat resistance. Meanwhile, the DLC film, having a high blockingeffect to oxygen, can suppress the light-emitting layer 713 fromoxidizing. Consequently, prevented is the problem of oxidation in thelight-emitting layer 713 during the following seal process.

[0181] Furthermore, a seal member 717 is provided on the passivationfilm 716 to bond a cover member 718. For the seal member 717 used may bean ultraviolet-rav-set resin. It is effective to provide therein asubstance having a hygroscopic effect or an antioxidant effect.Meanwhile, in this embodiment, for the cover member 718 used is a glasssubstrate, quartz substrate or plastic substrate (including a plasticfilm) having carbon films (preferably diamond-like carbon films) formedon the both surfaces thereof.

[0182] Thus, completed is a light-emitting device having a structure asshown in FIG. 15. Incidentally, it is effective to continuously carryout, without release to the air, the process to form a passivation film716 after forming a bank 712 by using a deposition apparatus of amulti-chamber scheme (or in-line scheme). In addition, with furtherdevelopment it is possible to continuously carry out the process up tobonding a cover member 718, without release to the air.

[0183] In this manner, n-channel TFTs 601, 602, a switching TFT(n-channel TFT) 603 and a current control TFT (n-channel TFT) 604 on thesubstrate 700.

[0184] Furthermore, as was explained using FIG. 15, by providing animpurity region overlapped with the gate electrode through an insulatingfilm, it is possible to form an n-channel TFT resistive to thedeterioration resulting from hot-carrier effect. Consequently, areliable light-emitting device can be realized.

[0185] Meanwhile, this embodiment shows only the configuration of thepixel portion and driver circuit. However, according to themanufacturing process in this embodiment, besides these, it is possibleto form on the same insulating member such logic circuits as a signaldivision circuit, a D/A converter, an operation amplifier, aγ-correction circuit or the like. Furthermore, a memory ormicroprocessor can be formed.

[0186] Furthermore, explained is a light-emitting device of thisembodiment having done the process up to sealing (or encapsulation) forprotecting the light-emitting elements, using FIG. 16. Incidentally, thereference numerals used in FIG. 15 are cited as required.

[0187]FIG. 16A is a top view showing a state done up to sealing of thelight-emitting elements while FIG. 16B is a sectional view taken on lineC-C′ in FIG. 16A. 801 designated by the dotted line is a source drivercircuit. 806 a pixel portion and 807 a gate driver circuit. In addition,901 is a cover member, 902 a first seal member and 903 a second sealmember. An encapsulation material 907 is provided at the insidesurrounded by the first seal member 902.

[0188] Incidentally, 904 is a wiring to transmit a signal to be inputtedto a source driver circuit 801 and gate driver circuit 807, to receive avideo signal or clock signal from an FPC (Flexible Print Circuit) 905 asan external input terminal. Incidentally. although only FPC is shownherein, the FPC may be attached with a printed wiring board (PWB). Thelight-emitting device in the description includes not only alight-emitting device main body but also such a device in the stateattached with an FPC or PWB.

[0189] Next, explanation is made on the sectional structure, by usingFIG. 16B. The pixel portion 806 and the gate driver circuit 807 areformed on the substrate 700. The pixel portion 806 is formed with aplurality of pixels each including a current control TFT 604 and a pixelelectrode 711 electrically connected to a drain thereof. Meanwhile, thegate driver circuit 807 is formed using a CMOS circuit having acombination of an n-channel TFT 601 and a p-channel TFT 602 (see FIG.14).

[0190] The pixel electrode 711 serves as an anode of a light-emittingelement. Meanwhile, banks 712 are formed on the both ends of the pixelelectrode 711. On the pixel electrode 711, a light-emitting layer 713and a cathode 714 of a light-emitting element are formed.

[0191] The cathode 714 serves also as a wiring common to all the pixelsand electrically connected to the FPC 905 by way of a connection wiring904. Furthermore, all the elements included in the pixel portion 806 andgate driver circuit 807 are covered by the cathode 714 and passivationfilm 567.

[0192] Meanwhile, a cover member 901 is bonded by the first seal member902. Incidentally, a resin-film spacer may be provided in order tosecure spacing between the cover member 901 and the light-emittingelements. An encapsulation material 907 is filled inside the first sealmember 902. Incidentally, the first seal member 902 and encapsulationmaterial 907 preferably uses epoxy resin. Meanwhile, the first sealmember 902 is preferably of a material to transmit water and oxygen to apossible less extent. Furthermore, the encapsulation material 907 maycontain a substance having a hygroscopic effect or an antioxidanteffect.

[0193] The encapsulation material 907 covering the light-emittingelements serves also as an adhesive to bond the cover member 901.Meanwhile, in this embodiment, as a material for the plastic substrateforming the cover member 901 can be used, FRP (Fiberglass-ReinforcedPlastics), PVF (polyvinyl Fluoride), Myler, polyester or acryl.

[0194] Meanwhile, after bonding the cover member 901 by using anencapsulation material 907, a second seal member 903 is provided so asto cover the side surface (exposed surface) of the encapsulationmaterial 907. For the second seal member 903 can be used the samematerial as the first seal member 902.

[0195] With the above structure, by encapsulating the light-emittingelements in the encapsulation material 907, the light-emitting elementscan be completely shielded from the outside. It is possible to preventthe intrusion, from the external, of the substance, such as water oroxygen, which accelerates the deterioration in the light-emitting layer.Thus, a reliable light-emitting device can be obtained.

[0196] The liquid crystal display device manufactured as above usessemiconductor film, which is uniformly crystallized by applying thelaser annealing of the present invention. and ensures enoughreliability. The liquid crystal display device can be used as a displayportion for an electronic appliance in various kinds.

[0197] Incidentally, this embodiment can be freely combined withEmbodiments 1 to 6.

[0198] Embodiment 9

[0199] Various electronic apparatuses (active matrix type liquid crystaldisplay device, active matrix type light emitting device and activematrix type EC display device) can be formed by applying the presentinvention. That is, the present invention can be applied to variouselectronic devices incorporating these electro-optical devices into thedisplay portion.

[0200] As such electronic apparatus, there are pointed out a videocamera, a digital camera, a projector, a head mount display (goggle typedisplay), a car navigation system, a car stereo, a personal computer, aportable information terminal (mobile computer, portable telephone orelectronic book) and the like. Examples of these are shown in FIGS.17A-17F, 18A-18D, and 19A-19C.

[0201]FIG. 17A shows a personal computer including a main body 3001, animage input portion 3002, a display portion 3003 and a keyboard 3004.The present invention can be applied to the display portion 3003.

[0202]FIG. 17B shows a video camera including a main body 3101, adisplay portion 3102, a voice input portion 3103, operation switches3104, a battery 3105 and an image receiving portion 3106. The presentinvention can be applied to the display portion 3102.

[0203]FIG. 17C shows a mobile computer including a main body 3201, acamera portion 3202, an image receiving portion 3203, an operationswitch 3204 and a display portion 3205. The present invention can beapplied to the display portion 3205.

[0204]FIG. 17D shows a goggle type display including a main body 3301, adisplay portion 3302 and an arm portion 3303. The present invention canbe applied to the display portion 3302.

[0205]FIG. 17E shows a player using a record medium recorded withprograms (hereinafter, referred to as record medium) including a mainbody 3401, a display portion 3402, a speaker portion 3403, a recordmedium 3404 and an operation switch 3405. The player uses DVD (DigitalVersatile Disc) or CD as the record medium and can enjoy music, enjoymovie and carry out game or Internet. The present invention can beapplied to the display portion 3402.

[0206]FIG. 17F shows a digital camera including a main body 3501, adisplay portion 3502. an eye contact portion 3503, operation switches3504 and an image receiving portion (not illustrated) etc. The presentinvention can be applied to the display portion 3502.

[0207]FIG. 18A shows a front type projector including a projectionapparatus 3601 and a screen 3602. The present invention can be appliedto the liquid crystal module 3808 forming a part of the projectionapparatus 3601.

[0208]FIG. 18B shows a rear type projector including a main body 3701. aprojection apparatus 3702, a mirror 3703 and a screen 3704. The presentinvention can be applied to the liquid crystal display device 3808forming a part of the projection apparatus 3702 and other drivercircuits.

[0209] Further, FIG. 18C is a view showing an example of a structure ofthe projection apparatus 3601 and 3702 in FIG. 18A and FIG. 18B. Theprojection apparatus 3601 or 3702 is constituted by a light sourceoptical system 3801, mirrors 3802, and 3804 through 3806, a dichroicmirror 3803, a prism 3807, a liquid crystal display apparatus 3808. aphase difference plate 3809 and a projection optical system 3810. Theprojection optical system 3810 is constituted by an optical systemincluding a projection lens. Although this embodiment shows an exampleof three plates type, this embodiment is not particularly limitedthereto but may be of, for example, a single plate type. Further, personof executing this embodiment may pertinently provide an optical systemsuch as an optical lens, a film having a polarization function, a filmfor adjusting a phase difference or an IR film in an optical path shownby arrow marks in FIG. 18C.

[0210] Further, FIG. 18D is a view showing an example of a structure ofthe light source optical system 3801 in FIG. 18C. According to thisembodiment, the light source optical system 3801 is constituted by areflector 3811, a light source 3812, lens arrays 3813 and 3814. apolarization conversion element 3815 and a focusing lens 3816. Further,the light source optical system shown in FIG. 18D is only an example andthis example is not particularly limited thereto. For example, a personof executing this example may pertinently provide an optical system suchas an optical lens, a film having a polarization function, a film foradjusting a phase difference or an IR film in the light source opticalsystem.

[0211] However, according to the projectors shown in FIG. 18, there isshown a case of using a transmission type electro-optical device and anexample of applying a reflection type electro-optical device or lightemitting device are not illustrated.

[0212]FIG. 19A shows a portable telephone including a main body 3901, asound output portion 3902, a sound input portion 3903, a display portion3904, an operation switch 3905, and an antenna 3906. The presentinvention can be applied to display portion 3904.

[0213]FIG. 19B shows a portable book (electronic book) including a mainbody 4001, display portions 4002, 4003, a record medium 4004, anoperation switch 4005 and an antenna 4006. The present invention can beapplied to display portions 4002 and 4003.

[0214]FIG. 19C shows a display including a main body 4101, a supportbase 4102 and a display portion 4103. The present invention can beapplied to display portion 4103. The display according to the inventionis advantageous particularly in the case of large screen formation andis advantageous in the display having a diagonal length of 10 inch ormore (particularly, 30 inch or more).

[0215] As has been described, the range of applying the presentinvention is extremely wide and is applicable to electronic apparatus ofall the fields. The electronic apparatus of the present invention can beimplemented by freely combined with the structures in Embodiments 1 to 7or Embodiment 8.

[0216] In accordance with the present invention, not only does it becomepossible to realize an optical system having a short optical path lengthwhen forming a longer linear shape beam by using a high output laseroscillator, but it becomes possible to achieve a laser irradiationapparatus having a small footprint.

[0217] Specifically, the optical path length of a long linear shape beamhaving a length that exceeds 300 mm can be made markedly shorter inaccordance with the present invention. In particular, the optical pathlength at the time of forming a linear shape beam by a conventionalmethod becomes on the order of 10 m for cases in which the length of thelinear shape beam is on the order of 1 m, and the footprint becomes verylarge. However, the optical path length can be kept to only half, 5 m,by applying the present invention. It is of course also possible toshorten the conventional optical path length of an optical system forforming a conventional linear shape beam, or that shorter than theconventional linear shape beam of the conventional optical system. Inparticular, the present invention is preferably applied to a process ofthe annealing for a semiconductor film. Semiconductor devicemanufacturing lines are normally located within a clean room having anextremely high cost per unit area, and therefore the reduction in thefootprint has an enormous effect in reducing costs.

What is claimed is:
 1. A laser irradiation stage comprising: making anirradiation surface for a beam that expands in a single direction into ashape that has curvature in a direction parallel to the singledirection.
 2. A laser irradiation stage according to claim 1, wherein:the curvature is provided in a negative direction with respect to thedirection at which the beam advances.
 3. A laser irradiation opticalsystem, comprising: a first means for expanding a beam in one direction;and a second means for establishing an irradiation surface for the beamthat is expanded in the one direction; wherein: the second means givesthe irradiation surface a shape having curvature in a direction parallelto the one direction.
 4. A laser irradiation optical system, comprising:a first means for expanding a beam in a first direction; a second meansfor concentrating light from the beam in a second direction orthogonalto the first direction; and a third means for establishing anirradiation surface for the beam that is expanded in the first directionand condensed in the second direction; wherein: the third means givesthe irradiation surface a shape having curvature in a direction parallelto the first direction.
 5. A laser irradiation optical system accordingto claims 4, wherein the first means makes the energy distribution ofthe beam uniform in the first direction.
 6. A laser irradiation opticalsystem according to claims 4, wherein the second means makes the energydistribution of the beam uniform in the second direction.
 7. The laserirradiation optical system according to claim 3, wherein the first meanscontains a cylindrical lens array or a cylindrical lens.
 8. The laserirradiation optical system according to claim 4, wherein the first meanscontains a cylindrical lens array or a cylindrical lens.
 9. The laserirradiation optical system according to claim 4, wherein the secondmeans contains a cylindrical lens array or a cylindrical lens.
 10. Thelaser irradiation optical system according to claim 3, wherein thecurvature is provided in a negative direction with respect to thedirection at which the beam advances.
 11. The laser irradiation opticalsystem according to claim 4, wherein the curvature is provided in anegative direction with respect to the direction at which the beamadvances.
 12. A laser irradiation apparatus comprising: a laseroscillator; a first means for expanding a laser beam emitted from thelaser oscillator in a first direction; a second means for condensing thelaser beam in a second direction that is orthogonal to the firstdirection; and a third means for establishing a laser beam irradiationsurface and moving the irradiation surface in the second direction,relative to the laser beam; wherein: the third means gives theirradiation surface a shape having curvature in a direction parallel tothe first direction.
 13. A laser irradiation apparatus according toclaim 12, wherein the first means makes the energy distribution of thelaser beam uniform in the first direction.
 14. A laser irradiationapparatus according to claim 12, wherein the second means makes theenergy distribution of the laser beam uniform in the second direction.15. A laser irradiation apparatus according to claim 12, wherein thefirst means contains a cylindrical lens array or a cylindrical lens. 16.A laser irradiation apparatus according to claim 12, wherein the secondmeans contains a cylindrical lens array or a cylindrical lens.
 17. Alaser irradiation apparatus according to claim 12, wherein the laseroscillator is an excimer laser, a YAG laser, a YVO₄ laser, a YLF laser,a YAlO₃ laser, or a glass laser.
 18. A laser irradiation apparatusaccording to claim 12, wherein the curvature is provided in a negativedirection with respect to the direction at which the laser beamadvances.
 19. A laser irradiation method comprising: expanding a laserbeam emitted from a laser oscillator in a first direction; condensingthe laser beam in a second direction that is orthogonal to the firstdirection; and irradiating the laser beam with respect to an irradiationsurface while moving relative to the irradiation surface in the seconddirection; wherein: the irradiation surface is formed into a shapehaving curvature in a direction parallel to the first direction.
 20. Alaser irradiation method according to claim 19, the energy distributionof the laser beam is made uniform in the first direction while expandingthe laser beam.
 21. A laser irradiation method according to claim 19,the energy distribution of the laser beam is made uniform in the seconddirection while condensing the laser beam.
 22. A laser irradiationmethod according to claim 19, wherein: the laser oscillator is anexcimer laser, a YAG laser, a YVO₄ laser, a YLF laser, a YAlO₃ laser, ora glass laser.
 23. A laser irradiation method according to claim 19,wherein: the curvature is provided in a negative direction with respectto the direction at which the laser beam advances.
 24. A method ofmanufacturing a semiconductor device, comprising: expanding a laser beamemitted from a laser oscillator in a first direction; condensing thelaser beam in a second direction that is orthogonal to the firstdirection; and performing annealing of a semiconductor film byirradiating the laser beam onto the semiconductor film while movingrelative to the semiconductor film in the second direction; wherein: thesemiconductor film is formed into a shape having curvature in adirection parallel to the first direction.
 25. A method of manufacturinga semiconductor device according to claim 24, wherein the energydistribution of the laser beam is made uniform in the first directionwhile expanding the laser beam.
 26. A method of manufacturing asemiconductor device according to claim 24, wherein the energydistribution of the laser beam is made uniform in the second directionwhile condensing the laser beam.
 27. A method of manufacturing asemiconductor device according to claim 24, wherein: the laseroscillator is an excimer laser, a YAG laser, a YVO₄ laser, a YLF laser,a YAlO₃ laser, or a glass laser.
 28. A method of manufacturing asemiconductor device according to claim 24, wherein: the curvature isprovided in a negative direction with respect to the direction at whichthe laser beam advances.
 29. A method of manufacturing a semiconductordevice according to claim 24, wherein the semiconductor device is adevice selected from the group consisting of a personal computer, avideo camera, a mobile computer, a goggle type display, a DVD player, aCD player, a front type projector, a rear type projector, a portabletelephone and a portable book.